1. Field of the Invention
The invention relates in general to hoist ring assemblies and, in particular, to a compact, high strength, multi-position hoist ring assembly.
2. Description of the Prior Art
Hoist ring assemblies have been widely used throughout industry to provide, for example, a means for quickly attaching a lifting device such as a crane or jack to a heavy object which is to be lifted. Hoist ring assemblies are generally considered to be critical safety items because, if a failure occurs, a heavy object may be dropped resulting in damage to people, the object, and its surroundings.
A variety of hoist ring assemblies having different load and swivel capabilities had previously been proposed. One variety, for example, is capable of swiveling throughout a complete 360 degree arc, and at the same time capable of being swung throughout an arc of substantially 180 degrees in a direction perpendicular to the 360 degree swivel arc, irrespective of the manner in which the fixture is attached to the load. For purposes of ease of description, a hoist ring assembly having this swiveling capability is sometimes herein referred to as a "multi-position fixture".
Previous multi-position fixtures, such as, for example, those described in Tsui et al U.S. Pat. Nos. 4,705,422 and 4,641,986, utilize a through bolt or socket screw to mount the assembly to an object to be lifted. However, the load capacity of these multi-position fixtures are restricted by the ability of the through bolt or socket screw to resist applied loads.
The workers in this field have recognized that there was a need to provide a multi-position fixture having a greater load capacity than that of previous through bolt or socket screw designs without substantially increasing manufacturing costs.
These and other difficulties of the prior art have been overcome according to the present invention.